Mark Duggan's family reacted with fury as an inquest jury found his death at the hands of a police marksman was lawful, despite him being unarmed when he was shot.

Dramatic scenes erupted in Court 73 of the historic Royal Courts of Justice as the jury of seven women and three men gave their conclusions, triggering emotional outbursts from family and friends who branded police "murderers" and hurled abuse.

Mr Duggan's brother Marlon shouted after the jurors as they left court, saying "f**k them", and angry supporters spilled from the courtroom and kicked at a door.

His sibling, whose death sparked protests that exploded into riots and looting across the country, was gunned down when police stopped the taxi in which he was travelling in Tottenham, north London, in August 2011.

At the culmination of the four-month inquest, the jury found that although the 29-year-old had a gun in the minicab, he most likely threw it onto a nearby grass verge as soon as the car came to a stop.

Their decision about the events surrounding his death sparked angry scenes outside the court building, where Mr Duggan's family claimed he was "executed" and branded the judgment "perverse".

Mr Duggan's aunt Carole Duggan said: "The majority of the people in this country know that Mark was executed. We are going to fight until we have no breath left in our body for Mark and his children."

His brother Shaun Hall said: "We came for justice today, we don't feel we are leaving with justice."

Police watchdog the Independent Police Complaints Commission (IPCC) said it was looking at new evidence that had emerged from the inquest, and the Duggan family are now considering whether to try to get the inquest conclusion judicially reviewed.

Their solicitor Marcia Willis-Stewart said: "On August 4, 2011 an unarmed man was shot down in Tottenham. Today we have had what we can only call a perverse judgment.

"The jury found that he had no gun in his hand and yet he was gunned down. For us that's an unlawful killing."

As her words were interspersed with shouting from a gathered crowd, she said the family were in a state of shock, adding: "They can't believe that this has been the outcome. No gun in his hand and yet he was killed - murdered as they have said, no gun in his hand."

Temperatures boiled over outside the Royal Courts of Justice as uniformed assistant commissioner Mark Rowley made a statement.

He could not be heard and protesters jostled waiting journalists. The angry crowd shouted "murderer" and "murdering scum". Others called out "who killed Mark Duggan? The police killed Mark Duggan."

As security staff tried to disperse the crowd and shield the officer, chants of "liars, racists, murderers, scum" rang out.

In the statement issued through Scotland Yard later, Mr Rowley said: "No officer sets out at the start of the day to run an operation that results in someone dying.

"So our sympathy today is with Mark Duggan's family. They have lost a loved one.

"But the task our officers face in making split-second decisions when confronting armed criminals means there is a risk - a very small risk - that this will happen.

"Armed criminals have shot dead more than 50 people in London in the last three and a half years. We send out well-trained, professional armed officers thousands of times a year to combat this threat, only firing shots once or twice."

He said he will meet the Duggan family to discuss the case.

Mr Duggan was being followed by officers who believed he planned to pick up a gun from another man, Kevin Hutchinson-Foster, and then move on to Broadwater Farm, also in Tottenham. Hutchinson-Foster has since been found guilty of supplying a gun to Mr Duggan.

The jury found that police had not done enough to gather and react to intelligence about the possibility of Mr Duggan collecting the gun.

But they found that the car had been stopped in a location and in a way that "minimised to the greatest extent possible recourse to lethal force".

There was beefed-up police presence across London tonight in a bid to avoid a repeat of the scenes of unrest during the immediate aftermath of the shooting.

Mr Rowley acknowledged that feelings were running high and called for a period of "sober reflection" as people absorbed the verdict.

"Ten ordinary men and women from across London have come to the conclusion that this is lawful," he told Channel 4 News.

"It is a very emotive time. You can understand the upset outside court from people interested in this case.

"But as much as when they were shouting and swearing and spitting at me they were exercising their democratic right to protest, part of a democracy is the rule of law and a jury has considered this for three months and come to a conclusion."

Dozens of protesters gathered outside Tottenham police station to protest.

There were chants of "racist murderers" and some carried placards with the slogan "No Justice No Peace".

Protester Kurtis Henville told reporters: "I pray to the Lord that somehow someone will actually realise that there is an injustice here and someone should be held accountable for what's happened.

"There was a wrongdoing, there's an eight to two verdict that he never had a gun in his hand when he was shot.

"So how did they still shoot him in cold blood and in broad daylight, and they're still saying that's lawful."

Another man, who did not want to give his name but said he was related to Mr Duggan, said: "They keep saying he was a notorious gang member with the Tottenham Mandem - no he was not.

"The police had warrants for six months to come forth and arrest him, I know this for a fact.

"They could have arrested him any time they wanted to but they wanted to make a show - trigger happy Metropolitan Police."